Make Candy Cookies
Tell yourself (or a visiting child's sugar-vigilant parents) that this is a "science" experiment. To prepare, gather all your data—also known as finding all your old Halloween, Christmas and goody-bag candy. Then make a batch of sugar cookies. Top each unbaked cookie with a piece of (this is crucial!) unwrapped candy. Secretly rearrange cookies on pan before putting in oven. Bake and cool. See who can identify the melted candy by observation and hypothesis. If that doesn't work, run a taste test.